git.ozlabs.org Git - ccan/blob - ccan/io/poll.c

   1 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
   2 #include "io.h"
   3 #include "backend.h"
   4 #include <assert.h>
   5 #include <poll.h>
   6 #include <stdlib.h>
   7 #include <sys/types.h>
   8 #include <sys/socket.h>
   9 #include <limits.h>
  10
  11 static size_t num_fds = 0, max_fds = 0, num_next = 0, num_finished = 0, num_waiting = 0;
  12 static struct pollfd *pollfds = NULL;
  13 static struct fd **fds = NULL;
  14 static struct timers timeouts;
  15
  16 static bool add_fd(struct fd *fd, short events)
  17 {
  18         if (num_fds + 1 > max_fds) {
  19                 struct pollfd *newpollfds;
  20                 struct fd **newfds;
  21                 size_t num = max_fds ? max_fds * 2 : 8;
  22
  23                 newpollfds = realloc(pollfds, sizeof(*newpollfds) * num);
  24                 if (!newpollfds)
  25                         return false;
  26                 pollfds = newpollfds;
  27                 newfds = realloc(fds, sizeof(*newfds) * num);
  28                 if (!newfds)
  29                         return false;
  30                 fds = newfds;
  31                 max_fds = num;
  32         }
  33
  34         pollfds[num_fds].fd = fd->fd;
  35         pollfds[num_fds].events = events;
  36         pollfds[num_fds].revents = 0; /* In case we're iterating now */
  37         fds[num_fds] = fd;
  38         fd->backend_info = num_fds;
  39         num_fds++;
  40         if (events)
  41                 num_waiting++;
  42
  43         return true;
  44 }
  45
  46 static void del_fd(struct fd *fd)
  47 {
  48         size_t n = fd->backend_info;
  49
  50         assert(n != -1);
  51         assert(n < num_fds);
  52         if (pollfds[n].events)
  53                 num_waiting--;
  54         if (n != num_fds - 1) {
  55                 /* Move last one over us. */
  56                 pollfds[n] = pollfds[num_fds-1];
  57                 fds[n] = fds[num_fds-1];
  58                 assert(fds[n]->backend_info == num_fds-1);
  59                 fds[n]->backend_info = n;
  60         } else if (num_fds == 1) {
  61                 /* Free everything when no more fds. */
  62                 free(pollfds);
  63                 free(fds);
  64                 pollfds = NULL;
  65                 fds = NULL;
  66                 max_fds = 0;
  67         }
  68         num_fds--;
  69         fd->backend_info = -1;
  70         close(fd->fd);
  71 }
  72
  73 bool add_listener(struct io_listener *l)
  74 {
  75         if (!add_fd(&l->fd, POLLIN))
  76                 return false;
  77         return true;
  78 }
  79
  80 static void adjust_counts(enum io_state state)
  81 {
  82         if (state == IO_NEXT)
  83                 num_next++;
  84         else if (state == IO_FINISHED)
  85                 num_finished++;
  86 }
  87
  88 static void update_pollevents(struct io_conn *conn)
  89 {
  90         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
  91
  92         if (pfd->events)
  93                 num_waiting--;
  94
  95         pfd->events = conn->plan.pollflag;
  96         if (conn->duplex) {
  97                 int mask = conn->duplex->plan.pollflag;
  98                 /* You can't *both* read/write. */
  99                 assert(!mask || pfd->events != mask);
 100                 pfd->events |= mask;
 101         }
 102         if (pfd->events)
 103                 num_waiting++;
 104
 105         adjust_counts(conn->plan.state);
 106 }
 107
 108 bool add_conn(struct io_conn *c)
 109 {
 110         if (!add_fd(&c->fd, c->plan.pollflag))
 111                 return false;
 112         adjust_counts(c->plan.state);
 113         return true;
 114 }
 115
 116 bool add_duplex(struct io_conn *c)
 117 {
 118         c->fd.backend_info = c->duplex->fd.backend_info;
 119         update_pollevents(c);
 120         return true;
 121 }
 122
 123 static void del_conn(struct io_conn *conn)
 124 {
 125         if (conn->finish)
 126                 conn->finish(conn, conn->finish_arg);
 127         if (timeout_active(conn))
 128                 backend_del_timeout(conn);
 129         free(conn->timeout);
 130         if (conn->duplex) {
 131                 /* In case fds[] pointed to the other one. */
 132                 fds[conn->fd.backend_info] = &conn->duplex->fd;
 133                 conn->duplex->duplex = NULL;
 134         } else
 135                 del_fd(&conn->fd);
 136         if (conn->plan.state == IO_FINISHED)
 137                 num_finished--;
 138         else if (conn->plan.state == IO_NEXT)
 139                 num_next--;
 140 }
 141
 142 void del_listener(struct io_listener *l)
 143 {
 144         del_fd(&l->fd);
 145 }
 146
 147 static void backend_set_state(struct io_conn *conn, struct io_plan plan)
 148 {
 149         conn->plan = plan;
 150         update_pollevents(conn);
 151 }
 152
 153 void backend_wakeup(struct io_conn *conn)
 154 {
 155         update_pollevents(conn);
 156 }
 157
 158 static void accept_conn(struct io_listener *l)
 159 {
 160         int fd = accept(l->fd.fd, NULL, NULL);
 161
 162         /* FIXME: What to do here? */
 163         if (fd < 0)
 164                 return;
 165         l->init(fd, l->arg);
 166 }
 167
 168 /* It's OK to miss some, as long as we make progress. */
 169 static void finish_and_next(bool finished_only)
 170 {
 171         unsigned int i;
 172
 173         for (i = 0; !io_loop_return && i < num_fds; i++) {
 174                 struct io_conn *c, *duplex;
 175
 176                 if (!num_finished) {
 177                         if (finished_only || num_next == 0)
 178                                 break;
 179                 }
 180                 if (fds[i]->listener)
 181                         continue;
 182                 c = (void *)fds[i];
 183                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
 184                         if (c->plan.state == IO_FINISHED) {
 185                                 del_conn(c);
 186                                 free(c);
 187                                 i--;
 188                         } else if (!finished_only && c->plan.state == IO_NEXT) {
 189                                 backend_set_state(c, c->plan.next(c, c->plan.next_arg));
 190                                 num_next--;
 191                         }
 192                 }
 193         }
 194 }
 195
 196 static void ready(struct io_conn *c)
 197 {
 198         backend_set_state(c, do_ready(c));
 199 }
 200
 201 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
 202 {
 203         if (!timeouts.base)
 204                 timers_init(&timeouts, time_now());
 205         timer_add(&timeouts, &conn->timeout->timer,
 206                   time_add(time_now(), duration));
 207         conn->timeout->conn = conn;
 208 }
 209
 210 void backend_del_timeout(struct io_conn *conn)
 211 {
 212         assert(conn->timeout->conn == conn);
 213         timer_del(&timeouts, &conn->timeout->timer);
 214         conn->timeout->conn = NULL;
 215 }
 216
 217 /* This is the main loop. */
 218 void *io_loop(void)
 219 {
 220         void *ret;
 221
 222         while (!io_loop_return) {
 223                 int i, r, timeout = INT_MAX;
 224                 struct timespec now;
 225
 226                 if (timeouts.base) {
 227                         struct timespec first;
 228                         struct list_head expired;
 229                         struct io_timeout *t;
 230
 231                         now = time_now();
 232
 233                         /* Call functions for expired timers. */
 234                         timers_expire(&timeouts, now, &expired);
 235                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
 236                                 struct io_conn *conn = t->conn;
 237                                 /* Clear, in case timer re-adds */
 238                                 t->conn = NULL;
 239                                 backend_set_state(conn, t->next(conn, t->next_arg));
 240                         }
 241
 242                         /* Now figure out how long to wait for the next one. */
 243                         if (timer_earliest(&timeouts, &first)) {
 244                                 uint64_t f = time_to_msec(time_sub(first, now));
 245                                 if (f < INT_MAX)
 246                                         timeout = f;
 247                         }
 248                 }
 249
 250                 if (num_finished || num_next) {
 251                         finish_and_next(false);
 252                         /* Could have started/finished more. */
 253                         continue;
 254                 }
 255
 256                 if (num_fds == 0)
 257                         break;
 258
 259                 /* You can't tell them all to go to sleep! */
 260                 assert(num_waiting);
 261
 262                 r = poll(pollfds, num_fds, timeout);
 263                 if (r < 0)
 264                         break;
 265
 266                 for (i = 0; i < num_fds && !io_loop_return; i++) {
 267                         struct io_conn *c = (void *)fds[i];
 268                         int events = pollfds[i].revents;
 269
 270                         if (r == 0)
 271                                 break;
 272
 273                         if (fds[i]->listener) {
 274                                 if (events & POLLIN) {
 275                                         accept_conn((void *)c);
 276                                         r--;
 277                                 }
 278                         } else if (events & (POLLIN|POLLOUT)) {
 279                                 r--;
 280                                 if (c->duplex) {
 281                                         int mask = c->duplex->plan.pollflag;
 282                                         if (events & mask) {
 283                                                 ready(c->duplex);
 284                                                 events &= ~mask;
 285                                                 if (!(events&(POLLIN|POLLOUT)))
 286                                                         continue;
 287                                         }
 288                                 }
 289                                 ready(c);
 290                         } else if (events & POLLHUP) {
 291                                 r--;
 292                                 backend_set_state(c, io_close(c, NULL));
 293                                 if (c->duplex)
 294                                         backend_set_state(c->duplex,
 295                                                           io_close(c->duplex,
 296                                                                    NULL));
 297                         }
 298                 }
 299         }
 300
 301         while (num_finished)
 302                 finish_and_next(true);
 303
 304         ret = io_loop_return;
 305         io_loop_return = NULL;
 306         return ret;
 307 }